// Copyright 2010, Willow Garage, Inc. All rights reserved.
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#ifndef MESSAGE_FILTERS__NULL_TYPES_HPP_
#define MESSAGE_FILTERS__NULL_TYPES_HPP_

#include <memory>

#include <rclcpp/rclcpp.hpp>

#include "message_filters/connection.hpp"
#include "message_filters/message_traits.hpp"

namespace message_filters
{

struct NullType
{
};
typedef std::shared_ptr<NullType const> NullTypeConstPtr;

template<class M>
struct NullFilter
{
  template<typename C>
  Connection registerCallback(const C &)
  {
    return Connection();
  }

  template<typename P>
  Connection registerCallback(const std::function<void(P)> &)
  {
    return Connection();
  }
};

namespace message_traits
{
template<>
struct TimeStamp<message_filters::NullType>
{
  static rclcpp::Time value(const message_filters::NullType &)
  {
    return rclcpp::Time();
  }
};
}  // namespace message_traits
}  // namespace message_filters

#endif  // MESSAGE_FILTERS__NULL_TYPES_HPP_
